[libpng16] Imported from libpng-1.6.3beta08.tar
[libpng16] Bump version to 1.6.3beta09
[libpng16] Fix spelling of "doclifter" in CHANGES and ANNOUNCE
[libpng16] Revised example.c to illustrate use of PNG_DEFAULT_sRGB and

PNG_GAMMA_MAC_18 as parameters for png_set_gamma().
[libng16] Revised contrib/tools/png-fix-too-far-back.c to check all compressed

chunks known to libpng.